In general, a hydraulic excavator which is a typical example of a construction machine is configured by an automotive lower traveling structure and an upper revolving structure rotatably mounted on the lower traveling structure, and a working mechanism liftably provided on a front side of the upper revolving structure.
The upper revolving structure is configured by a revolving frame forming a support structural body, an engine mounted on the revolving frame, an exhaust gas post-treatment device connected to an exhaust side of the engine and performing post-treatment of an exhaust gas exhausted from the engine, and a reduction agent tank storing a reduction agent to be supplied to the exhaust gas post-treatment device (Patent Document 1).